Aircraft



Jan. 14, 1941.

AIRCRAFT 3 Sheets- Sheet 1 Filed Oct. 1, 1957 Joseph KEWis'in Jr.

ATTORNEYS Jan. 14, 1941. M W R 2,228,311

AIRCRAFT Filed Oct. 1, 1937 3 Sheets-Sheet 2 F194 168 p a I *1 ATTORNEYSPatented Jan. 14, 1941 UNITED STATES AIRCRAFT Joseph M. Gwinn, Jrr,Buffalo, N. Y.

Application October 1,

Claims.

This invention relates to aircraft, and more particularly to controlmeans therefor.

In general, aircraft control elements comprise means for controlling thespeed, direction and 5 attitude of the craft movement under flight orground or water travel conditions, by changing the external force systemupon the aircraft. The control elements may be classified broadly asdirectional, longitudinal attitude, longitudinal thrust, and lateralattitude control means; and usually include specifically defined meanssuch as airfoil contour changing means, airfoil circulation'flow or liftchanging means such as moving surfaces, engine speed control means,controllable pitch propellers, air rudders, elevators, ailerons,horizontal stabilizers, vertical fins, flaps, tabs; wheel brakes, groundsteering means, and water steering means. Each of these control elementsmay be independently manipulatable by the pilot through means ofseparate actuating mechanisms, the proper correlation of which isnecessary to safe and proper flight. Unfortunately, the'propercorrelation of these control manipulations requires meticulous practiceat all times of a pilottechnique that may only be acquired as a resultof specific ability and intensive training. For instance, pilot errorssuch as excessive use .of the rudder under certain conditions ofvelocity and banking, or attempting to unduly stretch a glide willinevitably produce stalls and spins; and it is an object of the presentinvention to provide an aircraft embodying an improved control meanswhereby the possibility of the aircraft being directed into a dangerousattitude of flight through unskilled or careless piloting, iseliminated.

The invention contemplates the use of stop means for limiting thepossible movement of an aircraft control element; said stop means beingactuated in response to movement of other elements of the aircraft todifferent positions of adjustment, whereby movements of the controlmeans by the pilot are so limited as to be within an adjusted range ofmovement which is proper in view of prevailing conditions of motion.

This and more specific objects .and advantages of the'invention willbecome apparent from the following description of the typicalembodiments illustrated in the accompanying drawings.

In the drawings:

Fig. 1 is a fragmentary diagrammatic illustration in elevation oflongitudinal flight attitude control means embodying the invention;

Figsi2, 3 and 4 arefragnientary diagrammatic 192-7, Serial No. 166,846

Fig. 5 is an enlarged view of a detail of the mechanism shown in Fig. 1;

Fig. 6 is a diagrammatic plan view of an aircraft ground travel controlmechanism incorporating the principles of the invention;

Fig. '7 is a fragmentary diagrammatic plan view of directional flightcontrol means embodying the invention; and

Fig. 8 is a fragmentary diagrammatic view of variable lift control meansadapted to an application of the principles of the invention.

As shown in the drawings, and'referring now .particularly to Fig. 1, theinvention may be applied to conventional type airplane structurecomprising a front wing ID, a horizontal stabilizer l2, an elevator l4,and a wingflap [5. The elevator l4 is hingedly mounted upon a post IE,to which the stabilizer I2 is also pivo'tally connected, in any suitablemanner whereby the stabilizer and the elevator are both free to be movedindependently about the post I6 as a center.- The elevator I4 isprovided with a horn l8 rigidly extending therefrom to a point ofpivotal connection with a push-pull tube 22. The tube 22 is pivotallyconnected ,as at 24 to a rod 26 which is slidably mounted in a pair ofspaced bearings 28, which are supported on the aircraft fuselage in anysuitable manner. The opposite end of rod 26 is pivotally connected as at30 to a tube 32 for pilot manipulation as by means of a lever 34 whichis pivotally mounted upon the fuselage as at 36. The stabilizer I2 isprovided with a horn rigidly extending therefrom andcarrying at itsouter end in swiveling relation thereon an internally threaded nut 42. Athreaded bolt 44 engages within the nut 42 and is connected at itsforward end through means of a universal joint 46 with a rod 48 whichextends forwardly to the pilot compartment of the aircraft. A thrustbearing 45, mounted on the. aircraft fuselage maintainsthe bolt 44 infixed longitudinal relation with respect to the aircraft fuselage. Theforward end of the rod 48 is journaled in a swivelflbearing 50, and isprovided at its extreme end with a hand crank 52. Thus, the pilot mayturn the crank 52 to move the stabilizer l2 about its pivotal connectionto the post IE, to provide longitudinal balancing of the aircraft underdifferent conditions of flight.

A rod is pivotally connected at one end to an intermediate portion ofthe stabilizer post, as at 62, and is pivotally connected at itsopposite end, as by means of a pin 64, to one end of a cross arm 66. Thecross arm 66 is pivotally mounted, as at 66, upon a slide bar 66 whichis supported by means of a pair of spaced bearings 16 upon the fuselageof the aircraft. The cross .arm 65 is provided with an extending lug 12adapted to abut a lug 14 extending upwardly from the bar 26 when the bar26 is actuated in one direction of its sliding movement in the bearings'28. Thus, forward movement of the bar 26, in response to rearwardmovement of the pilot lever 64 to produce an upward movement of theelevator I4, will be limited by the co-action of the and thus shifts theposition of the stop 12 relative to the stop 14,'as illustrated inbroken lines in Fig. 1. Thus, it is seen that provision is made wherebymovement of the stabilizer upwardly shifts the stop 12 to a positionwhere it reduces the extent of possible upward movement of the.

elevator relative to the extent of possible upward movement of theelevatonwhen the stabilizer is v in a lowered position.

A beam 86 is pivotally mounted, as at 62, upon the bar 68. and has apivotal connection 64 at one end to a push-pull tube 66. The oppositeend of the tube 66 is pivotally connected, as at 66, to a throttle lever66, which in turn is pivotally mounted as by means of a pin 6| upon anysuitable supporting portion of the aircraft. A bar 62 connects the lever66 to the aircraft engine throttle for varying theengine speed inaccordance with movements by the pilot of the lever 66. The beam 66 isalso pivotally connected, as at 64, to one end of a rod 66, the otherend of whichis connected to a horn 66 extending rigidly from the wingflap IS. A pedal I66 is shown as being operatively connected to the flapII by means of a'rod I62 connected to the horn 66..

Thus, movement of the throttle lever "66 forwardly towards a throttle-onposition will transmit a rearward motion to the slide bar 66 and to thestop 12, and vice versa, regardless of the previous position of the stopI2 as determined by the settings of the stabilizer and the wing fiap. Ina likewise manner, the application of pressure upon the pedal I66, to.move the wing fiap l6 downwardly to a high lift position, will cause theslide bar 66 and the stop 12 to move rearwardly, regardless of theprevious position of the stop 12 as determined by the positions oftheother connected control elements. Thus, a system of interconnecting stopadjusting means is provided in which the stop adjusting effects of themanipulations'of' the various control elements of the aircraft aremerged into a compositeresultant. Hence, control movements in certaincombinations produce. cumulative stop adjusting effects, and in othercombinations proof the throttle, elevator, or wing flap adjustingmechanisms if some form of reversible actuating mechanism were employed,or any suitable form of friction or automatic 'or ratchet lock may beemployed to prevent actuation of the control elements except in responseto pilot manipulations of the respective actuating mechanisms.

For example, a form of automatic lock is shown in Fig. 5 as applied tothe throttle lever 66 in rwponse to forces imposed upon theinterconnecting link mechanism during adjustments of the other aircraftcontrol elements. The locking mechanism comprises a pin 6| which extendsfrom any suitable fixed supporting portion of the aircraft'fuselage anda concentric annular base member 266 which is also fixedly supportedupon a stationary portion of the aircraft structure and is provided witha perfectly round inner surface MI. in freely pivotable relation uponthe pin 6|. as by means of an aperture 262, and is formed with adownwardly extending arm 264 upon which are fixedly mounted a pair ofspaced laterally extending bosses 266.

A link 266 is pivotally mounted at its upper endupon the pin 6| and ispivotally connected at its lower end by means of a pin 2l6to the tube 66of Fig. 1. An intermediate! portion of the link 266 extends adjacent thearm 264 and between the bosses 266. The distance between the bosses 266is slightly greater than the width of the link 266 adjacent that point,and there is thus provided a lost motion connection between the lever 66and the link 266 whereby rocking movements of the lever 66 about thepivot pin 6| will impart reverse rocking movements to the link 264 andreciprocal movements of the tube 86 but with delayed action at thebeginning of each stroke of the lever 66.

The upper end of the link 266 is provided with an enlarged body portion2" which in front elevation is generally elliptical in shape andconcentric with the pin 6|, and is formed with edge portions 2 whichextend into the plane of the base member 266. Four lugs 2" formedintegral with the lever 66 extend therefrom in pairs on opposite sidesof the lever in substantially radiating relation with respect to the pin9| and laterally from the lever 66 and thence into the space between thesurfaces 261 and 2 l4, thus completing the outline of a pair of opposedarcuate shape chambers 2 l6.

The chambers 2" are thus similar and symmetrically disposed withrelation to the axes of the device, and are of tapering arcuate shape,being of less width at each of their ends than at their centers. A pairof balls 226 and 22l are arranged in the left hand chamber, as viewed inFig. 5, and a similar pair 222 and 226 are provided in 'the right handchamber, and in the case of each pair the balls are resiliently urgedapart by means of springs 224 towards the ends of the chambers 2l6. Theinner ends of the lugs 2l6 are adapted to bearagalnst the balls when thelever 66 is rotated upon the pin 9|. The balls 226, 22-|, 222, and 226are of such diameter that when they are disposed in the ends of thechambers they contact each of the surfaces 26| and 2H and thus providewedges to resist movements of the body 2 relative to the base 266.Hence, the balls normally look the link 266 against movements about thepivot pin 6| The throttle lever 66 is mounted Movement of the lever {Itothe right or left however, will first force the balls 222 and 22l or theballs 220 and 223, as the case may be, towards the centers of theirrespective chambers against the action of the springs 224, and thusrelease the balls from their locking action while the lost motionconnection between the bosses 206 and the link 208 is being. traversed.Further movement of the lever will then cause the link 208 to pivotabout the pin SI and simultaneously actuate the engine throttlerod 92and the stop actuating tube 86. Upon release of actuating pressure onthe lever 60, the springs 224 realign the lever 90 and the link 200 andmove the-balls into locking engagement with the members 200 and M2, thusautomatically locking the throttle control device in its'adiustedposition from whenceit-may only be moved in response to pilotmanipulation of the lever 90. It will be apparent that forcestransmitted to the tube 86 through connected mechanism for actuating theother control elements of the airplane will be prevented from moving thelink 208 or causing any change in the throttle setting.

Another form of control locking means is illustrated in Fig. 1 asapplied in connection with the push-pull I02 wherein a pair ofsemi-cylindrical shoes I04 are slidably fitted about the tube I02 andmaintained thereon by means of an embracing yoke I00. A rod I06 ismounted in screwthreaded relation in a threaded aperture through theupper portion of the yoke and has its lower end bearing against theupper shoe I04 and is adapted to be rotated manually by the aircraftpilot for alternate tightening and loosening of the shoes I04 withreference to the tube I02. The rod I06 is supported in verticallyslidable relation in a bearing I01 fixed to any convenient portion ofthe aircraft fuselage. Thus,

rotation of the threaded rod I06 into a shoe'- clampingposition providesa positive friction lock for preventing longitudinal movement in eitherdirection of thetube I02, and when so adjusted, the flaps I5 will bemaintained in'any predetermined position and will not be effected byforces transmitted through interconnected actuating mechanisms and tube96 in response to movements of other control members. Rotation of therod I06 is an opposite direction releases the clamping action of theshoes I04 and permits adjustment of the flap I5 and movement of the tubeI02.

It is contemplated that the elements of the devices shown herein may berearranged to provide any variety of efiects, to suit the requirementsof any particular aircraft and the type of performance desired. Forinstance, the embodiment shown in Fig. 1 and described herein willprovide for an increased restriction of possible uD-elevator movement asa result of. (0) adjustments of the stabilizer to raise its leadingedge; or of (b) movements of the throttle towards throttle-on position;or of (c) depression of the wing flaps. In some types of aircraft suchan arrangement will give the results desired because: (a) with leadingedge of stabilizer up, less up-eievator (with relation to its originalneutral angular position) is required to procure the same turningmoment; and (b) with the throttle-on, the increased air-stream over thetail surfaces reduces the degree of elevator deflection necessary toprocure-the same turning moment; and (c) with wing flaps down, anincreased downwash from the flaps increases the downward load on thetail surfaces and therefore reduces the magnitude of the down pressurerequired on the elevator to achieve any desired attitude of flight.

In other types of aircraft difierent reactions to these controladjustments may be required,

but it will be apparent to anyone skilled in the 1 art now theprinciples of the invention may be applied to procure any other resultor combination of results. Also, the relative magnitude of the effectsprocured by manipulation of the various control elements may be variedto suit different conditions of aircraft design and performance desiredby varying the arrangement and proportioning of the elements of the stopactuating mechanism. It is contemplated that the principles of theinvention may be applied with equal facility to limit the downwardmovement of the elevator by providing a stop actuating 'mechanism asillustrated in Fig. 4 wherein the elevator-actuated rod I26 is adaptedto be operatively connected to the elevator horn I0 and is provided witha stop lug I14 in a. manner similar to the arrangement of the rod 26 andthe lug 14 of Fig. 1. A crossobeam I65, carrying a stop lug I12, ispivotally conected at one end to a throttle and flap actuated slide rodI68 and at its opposite end to a stabilizer-actuated tube I60.

Thus, the arrangement is analogous to the ar-' rangement of thecorresponding parts 65, I2, 68 and in Fig. 1, with the exception that inthis latter form of arrangement the stop elements I12 and I14 areadapted to coact to limit the movement of the tube I26 toward the right(as viewed in the figure) and thus to limit movements of the elevator I4downwardly from its neutral free floating position. f

It is contemplated that the invention may be adapted to limit themovements of any other control element of an aircraft in any mannerdesired. For instance, Fig. 6 illustrates a ground wheel controlmechanism wherein a pair of directionally flxedground wheels 250 areshown as being provided with braking mechanisms operable by levers 252through means of a flexible cord and pulley system interconnected withan equalizer bar 255. A draw bar 256 is pivotally connected to theequalizer bar and to a pedal lever 251 which is fulcrumed upon someconvenient portion of the fuselage as at 259. Thus the application ofpressure upon the upper end of the pedal 251 will move the upper end ofthe pedal to the left, as viewed in Fig. 6, to actuate the levers 252for applying the wheel brakes.

A steerable. ground wheel 260 is shown as being mounted in directionallypivotable relation upon the fuselage as by means of a forked post 262supported on a bearing (not shown) supported upon a fuselage. A beveledgear 264 mounted concentrically upon and keyed to the post 262 and acompanion gear 266 mounted upon a steering post 260 provide means foradjusting the wheel 260 directionally upon rotation of the hand wheel210. A spur gear 212 is fixedly mounted upon the steering'column 268 forengagemen with a geared bar 214 which is slidably mounted upon thefuselage by means ofa pair of bearingsv 216. An intermediate portion 210of the geared bar is provided with a pair of Opp ed inclined sidesurfaces 280. The surfaces 200 are soarranged that when the steeringwheel 260 is in a straight forward position and the geared bar 214 is ina neutral position, the central point of connection of the surfaces 280coincides with the position of a boss 250 extending laterally from thepedal 251 when the pedal is moved forwardly to a brake-on position, asillustrated in broken lines. The members of the mechanism are soproportioned and arranged in spaced relation so that when the rack bar218 is in neutral position the pedal has ample room to travel to effecta full brake-on actuating movement. It will be apparent, however, thatwhenever the hand. wheel 218 is rotated to turn the steering wheel "8out of a straight line of travel position that the rack bar 214 will beshifted in either one of its possible directions of sliding movementwhereby the.

28'! by the pilot will be increasingly restricted as the steering wheel288 moves away from a straight line of travel position, and the severityof the braking action which it is possible for the pilot to impress uponthe system will vary reversely with the severity of any coincidentaldirectional turning maneuver. Hence the parts may be so proportioned andthe aircraft so designed that the pilot will be prevented from capsizingthe craft by too severe applications of brakes during turning maneuvers.

The upper end of the steerable wheel post 262 is provided with anintegral laterally extending arm 285. A stop block 281 provided with apair of outstanding spaced bosses 288 is slidably mounted in a bearing298 and pivotally connected as 2.12292 to the slotted end 284 of a bellcrank 288, the opposite end of which is pivotally connected to apush-pull tube 288 which is adapted to be actuated in response tomovements of an aircraft engine throttle lever 888. The bosses 288 ofthe stop block 28'! extend into the plane of movement of the arm 288,and are thus adapted to limit theangular rotation of the arm 288 aboutthe axis of the wheel post 282. It will be apparent that actuation ofthe throttle lever 888 to different positions of engine speed adjustmentwill simultaneously shift the stop block 281 longitudinally through thebearing 288, thus altering the distance between the bosses 288 and thewheel post 282 and the permissive angular rotation of the arm 288. Thus,means have been provided for limiting the amount of turning movementwhich may be applied to the steering wheel 288 by the pilot inaccordwith the aircraft engine speed.

Figure '7 illustrates an application of the principles of the inventionto an aircraft rudder and trim-tab mechanism wherein a rudder M8 ishinged as at 3l2 to the trailing edge of a vertical fin 8H. A pair ofhorns '8l8 extend laterally from the rudder and are connected toopposite control cables M8 for manipulation by the: pilot of theaircraft to procure directional turning movements of the rudder aboutthe line of hinge 8l2. A trim tab 828 is hingedly mounted .upon thetrailing edge of the rudder 8" and is provided with a laterallyextending horn 822 for actuation by the pilot through means of apush-pull. tube 324. The opposite end of the push-pull tube 828 isslidably mounted and maintained inaxial intersecting relation withrespect to the hinge M2 by means of a pair of guides or rollers 828 toavoid angular movements of the trim-tab relative to the rudder inresponse to pilot adjustments of the ruddersetting. The opposite end ofthe tube 828 is pivotally connected to one end of a push-pull tube 828,the other end of which is pivotally connected as at 828 to a cross bar888,. A push-pull tube 882 extending from. the

trim-tab pilot actuating mechanism (not shown) is also pivotallyconnected to the cross bar 888. The cross bar 888 is pivotally connectedas at 888 to'the aircraft fuselage. Hence longitudinal movements of thetube 882 in response to actua-' tion of the pilot adjusting mechanismrotates the cross bar 888 and actuates the tubes 828 and 828 to procureangular movement of the trim-tab 828 relative to the rudder 8| 8. Thecross bar 888 is provided with a pair of apertures 888 adaptedto receivethe cables 818 in sliding relation therein.

A bead 888 is fixedly mounted upon each of the cables 8l8 in similarspaced relation with respect to the opposite ends of the crossbar 888when the cross bar and the rudder 8|8 are both inneutral positions, saidbeads. being adapted to abut the cross bar upon movement of the ruddercable to restrict the maximum possible pilot movements of the rudderwithin predetermined limits. As illustrated in broken lines, when thetube 882 is moved to the left as viewed in Fig. '7, the cross bar ismoved to the broken line position and the trim-tab is rotated about itshinged connection to the rudder. This deflection of the trim taboutwardly into the adjacent airstream creates a turning'moment about theline of hinge M2 which results in moving the rudder 8" towardtheposition shown in broken lines.. This movement of the rudder isaccompanied by an adjusting movement of the rudder control cable 8 whichshifts the beads 888 to the broken line positions shown. Thus means havebeen provided whereby maximum permissible manipulation by the pilot ofthe aircraft rudder is limited in view of the relative position of thearticulated trim tab. Also, means have been provided whereby deflectionof the trim tab into the adjacent airstream accompanied by acorresponding shift in position of the rudder is accompanied by mutualadjustments of the related stop means whereby the neutral position ofthe rudder with respect to the stop means is unaltered, and equal ruddermovements in opposite directions from its neutral position are availableto the pilot.

Figure 8 illustrates an application of the principles of the inventionto a lift varying means of the moving skin airfoil type. In the figure,an airfoil 888 of the conventional wing type is illustrated as having aportion of its upper surface formed by the upper side of. an endlessflexible belt 882 supported upon a pair of opposed rollers 888. One ofthe rollers 888 is driven through means of a shaft 888 by an electricmotor M which derives its source of power from a bat-. teryB. v

The motor M is of the variable speed type, and a rheostat R is connectedin the power transmission line for controlling the speed of the motor inresponse to pilot adjustments of a rheostat lever 888. A pair ofpush-pull tubes 882 and 888 respectively are pivotally connected to therheostat lever 888, and at their opposite ends are slidably supported inbearings 888. Adjacent their respective ends the tubes 882 and 888 areprovided with laterally extending arms 884 and 888, re

'spectively, for cooperation with a similarly ex-' 2,228,811 ments ofthe tube 368 will be restricted in accordwith the relative setting ofthe rheostatlever 360, and that this form of the device may be employedto provide adjustably restricted movements of any pilot control memberwhich may be connected to the tube 368, the character of the restrictionvarying with changes in the speed with which the belt 352 is rotating.

It is contemplated that the invention may be applied to the restrictionof any means for changing the external force system upon an aircraftsuch as means for accomplishing directional, lateraLlOngitudinaIattitude, or longitudinal thrust control of an aircraft, either inconnection with flight or ground or water travel conditions; and theterm aircraft propeller or brakes in directions substantially parallelto the thrust axis of the aircraft. For instance, the possible degree ofrudder deflection may be restricted in conformity with the position ofthe landing flaps and/or the engine speed; and the range to which rudderdeflection is restricted may be varied in accordance with changes in thecondition of these control elements. For example, when flying with powerfull-on and under increased velocity conditions it is desirable toreduce the degree of possible rudto limit the degree of possiblepilot-manipulation of the throttle in accord with the attitude of theelevator, or the stabilizer, or the wing flaps, or the rudder, or of acombination of these control elements. Hence, it is contemplated thatthe invention has application to restriction of the actuation of anyaircraft flight control means, such as; an elevator, a stabilizer, awing flap, an aileron, an engine throttle, a rudder, a trim tab or anyother device for effecting a change of condition of aircraft movement,either in connection.

with flight or ground travel.

To provide for predetermined variations'in the relative magnitudes ofmaximum movements of a control element in opposite directions away fromits neutral position, the control element actuating means may bearranged in a predetermined functional relationship with respect tomovements of another of the aircraft control elements. For instance, therelative magnitudes 01' maximum movements of the flap H in oppositedirections away from its neutral trailing position may be caused to bevaried by arranging the stop and flap actuating means in a predeterminedfunctional relationship withrespect to movements of the stabilizer.Pivotal adjustments of the stabilizer l2 result in alterations of themean direction of the airstream surrounding the flap H, and for eachposition of adjustment of the stabilizer there is a different freefloating neutral position for the flap i4 involving a diflferent angularrelation between the center lines of the stabilizer and the flap. Hence,each different neutral position of the flap involves a diflerent angularrelation with respect to the aircraft fuselage, and

longitudinal thrust as used herein is intended to cover the forcesapplied through they 5 for each change in stabilizer position the flapwill automatically tend to assume a new neutral position under theinfluence of airstream pressures, and the neutral position of the tube22 and the stop II will shift accordingly. Thus, a second factoreffecting the relation of the stop elements is introduced into theoperation of the mechanism, and itwill be seen that the relative maximummovements of the flap above and below neutral positions are therebyvaried.

As illustrated in Fig. 2, the stop actuating means 'of Fig. 1 may be soarranged as to automatically control the ratio of the relative maximummovements of the control flap in opposite directions away from neutralpositions. In this form of arrangement, which also illustrates theinvention as being applied to an elevator restricting mechanism, thestabilizer I2 is pivotally mounted as at H0 upon the fuselage of theaircraft at a point intermedially of the stabilizer,

and the elevator is hinged as'at H to the trailing edge of thestabilizer. The elevator control tube 22 is slidably maintained at apredetermined constant distance from the axis of the pivotal connectionI ID, as by means of a. pair of spaced guide rollers I I 2 which arerotatably mounted upon any suitable support such as a horn H4 extendingrigidly from the stabilizer I2. Thus, movement of the stabilizer 12 toadjusted positions for lon' gitudinal balancing purposes actuates thestop 12 to adjusted positions in a manner similar to that explainedhereinabove in connection with Fig. 1; and adjustment of the stabilizerto a nosedown position moves the stop I2 forwardly, or to'the left, asillustrated in brokenlines in Fig. 2.

In response to the change in the mean direction of the airstreamimmediately behind the stabilizer l2 caused by the adjustment of thestabilizer from the solid line position to the broken line position ofFig. 2, the elevator [4 will move from its original free floatingneutral position E1 to a new free floating neutral position along alineEz involving adifferent angular relation with respect to the foreand aft center line S oi the stabilizer. Forinstance, assuming the solidline position of the stabilizer to be at a zero angle of attack, thenthe solid line position of the elevator M will represent a neutral freefloating trailing position, wherein E, (the aerodynamic center lineposition of the elevator) will coincide with Z (the aerodynamic centerline of the stabilizer). broken line position, the elevator will move toa position along line E2, which will be disposed at some angleintermedially of the angles at which lines Z and S (the aerodynamiccenter line of' the stabilizer in its adjusted broken line position) aredisposed. Hence, the elevator horn [8 will be moved 'forwardly'and willprocure a corresponding forward adjustingmovement of the stop I4, as,for example, to the broken line position indicated in Fig. 2. Therelative magnitudes of the simultaneous adjustments of the stops l2 andM under such conditions'will determine the net difl'erence in relativepositions of the stop elements 12 and 14. In connection witheitherposition of stabilizer adjustment, however, the elevator is in a neutralfree floating position behind the stabilizer. Hence, the amount ofpossible movement of the elevator l4 from a neutral positionupwardly'has been varied accordingly.

The maintenance of any predetermined spaced relation between theelevator control tube 22 and the stabilizerpivotal axis H0 willpermitthe ele- Upon movement of the stabilizer to its Fig. 3 illustratesanother form of the inven-- tion embodying means for varying the ratiosof movements of a control element in opposite directions away fromneutral. In this instance, the invention is also shown as being appliedto a restrictive control mechanism for the'elevator I4, but obviously itmay have application to any other control element of an aircraft. Theelevator is provided with a horn I8 to which is operatively connectedone end of a push-pull tube 22. The opposite endofthe tube 22 ispivotally connected to a pilot lever I I6 which is pivotally mountedupon the aircraft at I I1, and is provided with a lower angularlyextending portion II8. The portion I I8 is provided with a slot I I9 forreceiving therein a headed pin I20 for maintaining the end of the .tube22 and the lever portion H8 in sliding and pivotallyconnected relation."An engine throttle lever I23, in the form of -a bell crank, isconnected at its offset end with a control rod I24 which in turnsupports a hanger I25 embracing the adjacent end of the tube 22.

Hence, pivotal movements of the throttle lever I23 to alter the aircraftengine speed will raise or lower, as the case may be, the adjacent end01 the tube 22 with, relation to the point of pivotal connection II] ofthe elevator control lever II6 to the aircraft frame structure. A pairof opposed stop lugs I2I and I22 mounted upon and extending from anysuitable supporting structure of the aircraft are provided to positivelylimit the possible movements of the control lever H5 in either directionof its movement.

Thus, it will be apparent that manipulation of the throttle lever I23,as to the broken line posi- 5 tion of Fig. 3, will lower the tube 22 andmove the the elevator Il upwardly and downwardly with.

elevator lever I I6 about its-pivot II! to the broken line position asindicated. Thus, the lever H6 is shifted in relation to the stops I2Iand I22, and the ratio of possible maximum movements of respect to itsneutral position has been altered. Also, the possible total combined upand down motion of the elevator has been increased.

It is contemplated that the invention is adapted to application inconnection with automatically actuated aircraft control means. Forinstance, as shown by way of illustration in Fig. 1, the -elevator I4may be provided with an automatic actuating means as indicated at Awhich is operably coupled with the lever 34 by means of a tube I 35; andin a similar manner, any one of the other control elements of anaircraft may be coupled withan automatic actuating means and adjustablerestrictive means for limiting the operation of the automatic actuatingmeans. Furthermore, any suitable form of gravity-controlled orgyroscopic mechanism may be interconnected with a stop element adjustingmeans to provide an automatically adjusted restrictive-device forlimiting the manipulation of an al fcraft control element in response tochanges in night conditions which effect the condition of the automaticcontrol device. The invention contemplates.

the art that the invention is not so limited but that various changesmay be made therein without departing from the spirit of the inventionor from the scope of the appended claims.

'I claim:

1. In an aircraft, a plurality of control elements consisting of atleast three control elements and separate pilot-operable actuatin meansfor each of said control elements, stop means for limiting the possiblepilot manipulation of one of said control elements, and means associatedwith each of the other of said control actuating means and with saidstop means in such manner that manipulations of the other of saidcontrol elements produce stop adjusting effects which are resolved intoa single stop adjusting effect for adjustment of said stop wherebymanipulation of said first mentioned control means is limited in accordwith conditions of motion as determined by control effects produced bythe other of said control elements.

2. man aircraft, a plurality of control elements comprising at leastthree control elements and separate pilot-operable actuating means foreach of said control elements, stop means for limiting the possiblepilot manipulation of one of said control elements, and means associatedwith each of the other of said control actuating means and with saidstop means in such manner that manipulation of either of the other ofsaid control elements alters the ratio of possible movements of said oneof said control elements in opposite directions away from a neutralposition.

3. In an aircraft, a pilot adjustable engine power control means. anelevator, a pilot adjustable elevator control means, and, a positivestop member movable in response to adjustment of said power controlmeans and operatively associated with said elevator control means forincreasingly limiting possible adjustments by'the pilot of said elevatorcontrol means for upward tilting of said elevator under increasing powerconditions.

4. In an aircraft, a pilot adjustable engine power control means, anelevator, a pflot adjustable elevator control means, and a positive stopmember movable in response to adjustment of said power control means andoperatively associated with said elevator control means for increasinglylimiting possible adjustments by the pilot of said elevator controlmeans for downard tilting of said elevator under decreasing powerconditions.

5. In an aircraft, a pilot adjustable engine poweer control means, awing flap, a pilot adjustable wing flap control means, and a positivestop member movable in response-to adjustment of said power controlmeans and operatively associated with said wing flap control means forincreasingly restricting adjustments by the pilot of said wing flapcontrol means for downward tilting ofsaid wing flap under increasingpower conditions.

- JOSEPH M. GWINN, JR.

